The objective of this Phase II study is to develop novel hydrogel-based tissue expanders that have delayed expansion with the property to be reshaped by the surgeon. Current tissue expanders either require external inflation or are immediately swelling potentially re-opening the surgical implant site. Also, no current tissue expander is re-shapable, reducing their usefulness. Phase I research showed that hydrogels could be generated which had the desirable properties of reshapability, 2-3 weeks of the lag time prior to expansion, and post-degradation high mechanical strength. These properties could also be controlled by changing chemical composition of the hydrogels. Phase II research will focus on combining these desired properties into a few optimized prototypes and subsequently testing of these prototypes for safety and efficacy in animal models to generate tissue expanders ready for clinical trials. Specific Aim 1 is to synthesize more delayed swelling hydrogels each possessing three requirements ideal for tissue expanders. Akina has already identified one hydrogel prototype with desired properties. Six optimized prototypes will be selected to carry forward to the next stages. Specific Aim 2 is to examine the efficacy of selected tissue expanders in the rat model. This will screen the six prototypes down to the one which is most effective as a tissue expander. Specific Aim 3 is to examine the toxicity of the tissue expander identified in Aim 2 and test its efficacy in the dog model. Safety of this prototype will be determined using ISO 10993 testing to ensure the hydrogels are non-toxic and biocompatible. An intra-oral dog model will be utilized to determine the efficacy of the hydrogel prototype in a setting representative of dental use. Specific Aim 4 is to produce a delayed swelling tissue expander ready for clinical studies. The hydrogel prototype that has been shown to be safe and effective in the animal studies will be used to prepare application to the Food and Drug Administration (FDA) for approval of clinical studies. Successful completion of this Phase II study will generate novel, delayed-swelling, hydrogel based, tissue expanders which do not suffer the drawbacks of current tissue expansion technologies. These tissue expanders will be easily re-shapable, have delayed expansion, have good post-degradation strength, and be shown to be safe and effective in animal models. Akina's delayed swelling tissue expander will provide substantial advantages over the current tissue expander on the market, and thus immediate impact to the field is expected. PUBLIC HEALTH RELEVANCE: This Phase II SBIR project will generate re-shapable, delayed-expansion, hydrogel-based tissue expanders for use in dental and other reconstructive surgeries. These tissue expanders will overcome problems associated with current technology, such as eliminating exterior equipment and allowing custom fitting of the expander to the tissue by the surgeon. This technology will reduce the incidence of morbidity associated with this surgery, thus promoting general public health.